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A 1.2 Ma record of glaciation and fluvial discharge from the West European Atlantic margin ArchiMer
Toucanne, Samuel; Zaragosi, S.; Bourillet, Jean-francois; Gibbard, P. L.; Eynaud, F.; Giraudeau, J.; Turon, J. L.; Cremer, M.; Cortijo, E.; Martinez, P.; Rossignol, L..
The correlation of continental sedimentary records with the marine isotope stratigraphy is a challenge of central importance in Quaternary stratigraphy, particularly in Western Europe where long records of glaciation on land areas are particularly rare. Here we demonstrate for the first time the interrelationship of events during the last 1.2 Ma in an ocean-sediment core from the Bay of Biscay (NE Atlantic), SW of the Channel. The identification of discharge variations from tributary river systems to the 'Fleuve Manche' palaeoriver during glacio-eustatic sea-level lowstands demonstrates the correlation of the marine sediment stratigraphy to the expansion and recession of the European ice-sheets. The amplitude and chronology of European ice-sheet...
Tipo: Text Palavras-chave: Middle pleistocene transition; Ice sheet dynamics; Sea level; Climate change; North Atlantic; English channel; Heinrich events; Fleuve manche; Deep; Origin.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6956.pdf
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A new classification scheme of European cold-water coral habitats: implications for ecosystem-based management of the deep sea ArchiMer
Davies, J. S.; Guillaumont, Brigitte; Tempera, Fernando; Vertino, A.; Beuck, L.; Olafsdottir, S. H.; Smith, C. J.; Fossa, J. H.; Van Den Beld, Inge; Savini, A.; Rengstorf, A.; Bayle, Christophe; Bourillet, Jean-francois; Arnaud-haond, Sophie; Grehan, A..
Cold-water coral (CWC) habitats can form complex structures which provide refuge, nursery grounds and physical support for a diversity of other living organisms, but despite their ecological significance, CWCs are still vulnerable to human pressures such as fishing, pollution, ocean acidification and global warming Providing coherent and representative conservation of vulnerable marine ecosystems including CWCs is one of the aims of the Marine Protected Areas networks being implemented across European seas and oceans under the EC Habitats Directive, the Marine Strategy Framework Directive and the OSPAR Convention. In order to adequately represent ecosystem diversity these initiatives require a standardised habitat classification that organises the variety...
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Ano: 2017 URL: http://archimer.ifremer.fr/doc/00383/49474/49961.pdf
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ACTION RECOPLA - Inventaire et bancarisation des données de Géosciences Marines pour les façades Atlantique, Manche et Méditerranée ArchiMer
Gautier, Emeric; Kerjean, Mathieu; Satra Le Bris, Catherine; Bourillet, Jean-francois.
This report presents the inventory work realized for all the Marine Geoscience dept data acquired on the French continental shelf. It lists the bathymetric, seismic and backscattering data acquired, processed and interpreted in English Channel, Atlantic and Mediterranean. All the maps used for this inventory are available within the GIS "Manche Atlantique" and "Golfe du Lion".
Tipo: Text Palavras-chave: Inventaire; SIG; Manche; Atlantique; Méditerranée; Bathymétrie; Imagerie acoustique; Sismique; Données brutes; Traitées; Interprétées; GeoBIS; Inventory; GIS; Englsih Channel; Atlantic; Mediterranean Sea; Backscatter; Seismic; Raw; Processed; Interpreted data; GeoBIS.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00014/12558/9426.pdf
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Activity of the turbidite levees of the Celtic-Armorican margin (Bay of Biscay) during the last 30,000 years: Imprints of the last European deglaciation and Heinrich events ArchiMer
Toucanne, Samuel; Zaragosi, S; Bourillet, Jean-francois; Naughton, F; Cremer, M; Eynaud, F; Dennielou, Bernard.
High-resolution sedimentological and micropaleontological studies of several deep-sea cores retrieved from the levees of the Celtic and Armorican turbidite systems (Bay of Biscay - North Atlantic Ocean) allow the detection of the major oscillations of the British-Irish Ice Sheet (BIIS) and 'Fleuve Manche' palaeoriver discharges over the last 30,000 years, which were mainly triggered by climate changes. Between 30 and 20 cal ka, the turbiditic activity on the Celtic-Annorican margin was weak, contrasting with previous stratigraphic models which predicted a substantial increase of sediment supply during low sea-level stands. This low turbidite deposit frequency was most likely the result of a weak activity of the 'Fleuve Manche' palaeoriver and/or of a...
Tipo: Text Palavras-chave: Turbidites; Heinrich events; LGM; Last deglaciation; Palaeoriver; Fleuve Manche; British irish ice sheet; Bay of Biscay.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-3729.pdf
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Are trawl marks a good indicator of trawling pressure in muddy sand fishing grounds? ArchiMer
Merillet, Laurene; Kopp, Dorothee; Robert, Marianne; Salaun, Michele; Mehault, Sonia; Bourillet, Jean-francois; Mouchet, Maud.
The development of the vessel monitoring system (VMS) in the recent years has offered high-resolution data to map the distribution and intensity of fishing activities and contributed to enhancing the potential identification of fishing impacts. However, impacts could vary at very small scale and the resolution of VMS data might not be fine enough. Other proxy could be used, such as trawl marks visible on the seabed observed by underwater video or side-scan sonar to evaluate small-scale trawling effort. In the Bay of Biscay, an underwater video survey of the Nephrops norvegicus fishing ground was conducted and provided environmental characteristics such as depth and number of trawl marks at 152 transects. The relevance of observed trawl marks as a...
Tipo: Text Palavras-chave: Bay of Biscay; Fishing intensity; Sediments; Underwater video; Vessel monitoring system.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00410/52112/52854.pdf
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Behaviour Of A Piston Corer From Accelerometers And New Insights On Quality Of The Recovery ArchiMer
Bourillet, Jean-francois; Damy, Gilbert; Dussud, Loic; Sultan, Nabil; Woerther, Patrice; Migeon, Sebastien.
Various observations pointed out that cores performed with gravity piston corer show signifi cant distortions mainly located at the top of the core. A series of 15 cores were performed at the same location on a submarine sand wave (Var canyon, France). Six different settings of the corer – three freefall heights and three slacks of the piston cable – were tested, including duplicates. Two accelerometers recorded simultaneously the movements of the core tube and the movements of the triggering arm. Then the z displacements were obtained by a double integration versus time of the measured acceleration. The analyses of results allowed the authors to estimate the amplitude and the duration of the elastic recoil of the aramid cable, andto distinguish four steps...
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Ano: 2007 URL: http://archimer.ifremer.fr/doc/00071/18198/15766.pdf
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Buried fluvial incisions as a record of Middle-Late Miocene eustasy fall on the Armorican Shelf (Bay of Biscay, France) ArchiMer
Paquet, Fabien; Menier, David; Estournes, Guilhem; Bourillet, Jean-francois; Leroy, Pascal; Guillocheau, Francois.
High-resolution seismic data have been acquired in June 2008 on the Armorican Shelf (AS), in the northern Bay of Biscay, in order to reassess its stratigraphic architecture in detail and to study the impact of eustasy, tectonic and sediment delivery on the margin sedimentary record. Several profiles show fluvial-type incisions of several tens of meters (up to 54 m) associated to a widespread erosion surface. Several hypotheses are proposed for the stratigraphic position of this surface and incisions. We suggest Middle to Late Miocene age. Considering the relatively quiescent tectonic activity of the margin, we infer that the relative sea-level fall responsible of aerial incision on the Miocene shelf is eustasy-related. We propose the attested...
Tipo: Text Palavras-chave: Armorican Shelf; Incised valleys; Miocene; Eustasy; Passive margin.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00001/11200/8048.pdf
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Cenozoic tectonics of the Western Approaches Channel basins and its control of local drainage systems ArchiMer
Le Roy, Pascal; Gracia-garay, Claire; Guennoc, Pol; Bourillet, Jean-francois; Reynaud, Jean-yves; Thinon, Isabelle; Kervevan, Patrick; Paquet, Fabien; Menier, David; Bulois, Cedric.
The geology of the Channel Western Approaches is a key to understand the post-rift evolution of the NW European continental margin in relation with the Europe/Africa collision. Despite considerable evidence of Tertiary tectonic inversion throughout the Channel basin, the structures and amplitudes of the tectonic movements remain poorly documented across the French sector of the Western Approaches. The effect of the tectonic inversion for the evolution of the "Channel River", the major system that flowed into the English Channel during the Plio-Quaternary eustatic lowstands, also needs to be clarified. Its drainage basin was larger than the present-day English Channel and constituted the source of terrigenous fluxes of the Armorican and Celtic deep sea...
Tipo: Text Palavras-chave: English Channel; Western Approaches basins; Cenozoic; Palaeovalley; Seismic stratigraphy; Tectonic inversion.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00056/16706/15776.pdf
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Cold-water coral habitats in submarine canyons of the Bay of Biscay ArchiMer
Van Den Beld, Inge; Bourillet, Jean-francois; Arnaud-haond, Sophie; De Chambure, Laurent; Davies, Jaime S; Guillaumont, Brigitte; Olu, Karine; Menot, Lenaick.
The topographical and hydrological complexity of submarine canyons, coupled with high substratum heterogeneity, make them ideal environments for cold-water coral (CWC) habitats. These habitats, including reefs, are thought to provide important functions for many organisms. The canyons incising the continental slope of the Bay of Biscay have distinct morphological differences from the north to the south. CWCs have been reported from this basin in the late 19th century; however, little is known about their present-day distribution, diversity and environmental drivers in the canyons. In this study, the characteristics and distribution of CWC habitats in the submarine canyons of the Bay of Biscay are investigated. Twenty-four canyons and three locations...
Tipo: Text Palavras-chave: Cold-water corals; Habitats; Submarine canyons; Bay of Biscay; NE Atlantic; ROV; Towed camera; Distribution.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00382/49343/49733.pdf
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Comments to Westaway and Bridgland - 'Causes, consequences and chronology of large-magnitude palaeoflows in Middle and Late Pleistocene river systems of northwest Europe' ArchiMer
Toucanne, Samuel; Zaragosi, S.; Eynaud, F.; Bourillet, Jean-francois; Lericolais, Gilles; Gibbard, P. L..
Westaway and Bridgland (Earth Surface Processes and Landforms 35: 1071–1094, 2010) discuss the causes, the consequences and the chronology of large-magnitude palaeoflows in Pleistocene river systems of northwest Europe. Based on their calculations, these authors suggest that the combined effects of meltwater from Alpine glaciers, rainfall, snowmelt and melting of permafrost during Heinrich Events (HEs) explain the large-magnitude discharges of the Fleuve Manche palaeoriver which punctuated the last glacial period. This comment identifies some approximations and inconsistencies regarding (i) the timing of the last massive Fleuve Manche palaeoriver discharge and its relation to the de-glacial pattern of the British-Irish Ice Sheet (Point 1); (ii) the...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00041/15205/12532.pdf
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Deglacial laminated facies on the NW European continental margin: The hydrographic significance of British-Irish Ice Sheet deglaciation and Fleuve Manche paleoriver discharges ArchiMer
Eynaud, F; Zaragosi, S; Scourse, J; Mojtahid, M; Bourillet, Jean-francois; Hall, I. R.; Penaud, A; Locascio, M; Reijonen, A.
[1] We have compiled results obtained from four high sedimentation rate hemipelagic sequences from the Celtic sector of the NW European margin ( NE Atlantic) to investigate the paleoceanographic and paleoclimatic evolution of the area over the last few climatic cycles. We focus on periods characteristic of deglacial transitions. We adopt a multiproxy sedimentological, geochemical, and micropaleontological approach, applying a sampling resolution down to ten microns for specific intervals. The investigation demonstrates the relationships between the Bay of Biscay hydrography and the glacial/deglacial history of both the proximal British-Irish Ice Sheet (BIIS) and the western European continent. We identify recurrent phases of laminae deposition concurrent...
Tipo: Text Palavras-chave: Paleoceanography : micropaleontology; Paleoceanography : abrupt/rapid climate change; Paleoceanography : glacial; Planktonic microfossils; Ice rafted detritus; Freshwater pulse/discharge; Laminated sediments; Glacial terminations; Celtic margin.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2606.pdf
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Dynamics of gas hydrate: case of the Congo continental slope ArchiMer
Sultan, Nabil; Foucher, Jean-paul; Cochonat, Pierre; Tonnerre, T; Bourillet, Jean-francois; Ondreas, Helene; Cauquil, E; Grauls, D.
A numerical model is developed to study the temperature effect on stability and phase transformation of gas-hydrate. The model uses a mathematical formulation based on the enthalpy form of the conservation law of energy. The use of the enthalpy form instead of the temperature form as often done in the literature has made the problem numerically simpler. The model is then applied to describe the effect of sea bottom temperature variations on the stability of gas hydrate occurrences and on the seafloor reflectivity in sediments of the Congo continental slope. Indeed, a migrating seafloor reflectivity front is observed on 3D seimic images from two surveys performed 6 months apart and interpreted as a migrating gas hydrate stability zone. Seawater temperature...
Tipo: Text Palavras-chave: Temperature; Stefan problem; Seafloor reflectivity; Gas hydrate; Heat flow; Finite difference; Continental margins.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-702.pdf
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Evaluation of the risk of marine slope instability: A pseudo-3D approach for application to large areas ArchiMer
Sultan, Nabil; Cochonat, Pierre; Bourillet, Jean-francois; Cayocca, Florence.
This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried...
Tipo: Text Palavras-chave: Shear strength; Slope stability; Safety factor; Marine sediment; Finite element; Finite difference; Failure.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/publication-698.pdf
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External controls on turbidite sedimentation on the glacially-influenced Armorican margin (Bay of Biscay, western European margin) ArchiMer
Toucanne, Samuel; Zaragosi, Sebastien; Bourillet, Jean-francois; Dennielou, Bernard; Jorry, Stephan; Jouet, Gwenael; Cremer, Michel.
Sequence stratigraphic models predict increased sediment delivery to deep-water areas during sea-level lowstand. The Armorican margin (Bay of Biscay, western European margin) is an interesting area to test this hypothesis because the margin has a wide continental shelf, still partly flooded during sea-level lowstand, and the Armorican turbidite system has experienced fluctuating sediment fluxes since the last glacial period. The stratigraphic response of the Armorican turbidite system to sea-level oscillations and climate changes was assessed for the last 35,000 years through the study of the Guilcher, Crozon and Audierne levees. Millenial-timescale resolution chronostratigraphy allowed us to reconstruct the sediment accumulation and turbidite frequency,...
Tipo: Text Palavras-chave: Armorican margin; Bay of Biscay; Turbidite systems; Turbidity currents; Levee growth; External forcing; Deglaciation; Source-to-sink.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00070/18147/15708.pdf
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First observations of deep-sea coral reefs along the Angola margin ArchiMer
Le Guilloux, E.; Olu, Karine; Bourillet, Jean-francois; Savoye, Bruno; Iglesias, S. P.; Sibuet, Myriam.
The West African continental slope is an important theatre for geological survey prospecting and drilling for hydrocarbons but little is known about local deep-sea biological communities at these depths. While shallow-water reefs are common and well-known features in the tropics, only few records of deep-water corals exist at low latitudes, and most of them have been reported by historical oceanographic cruises undertaking circum-navigations of the world. This study, based on a multi-disciplinary approach, presents a description of newly discovered deep-water coral reef communities along the Angola margin. Data from ROV, multibeam bathymetry, side-scan sonar and seismics from a deep-towed acoustic system (SAR) were used to describe the morphology of the...
Tipo: Text Palavras-chave: Lucinids; Habitat mapping; ROV; Lophelia pertusa; Deep sea corals; Angola margin.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-7403.pdf
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Fluid emissions at the Aquitaine Shelf (Bay of Biscay, France): A biogenic origin or the expression of hydrocarbon leakage? ArchiMer
Dupre, Stephanie; Berger, Laurent; Le Bouffant, Naig; Scalabrin, Carla; Bourillet, Jean-francois.
Fishery acoustic surveys conducted in the Bay of Biscay and dedicated to monitoring and predicting pelagic ecosystem evolution reveal numerous active seeps on the Aquitaine Shelf, east of the shelf break, at water depths ranging from 140 to 185 m. Some acoustic anomalies recorded in the water column with hull-mounted single and multibeam echosounders are clearly caused by fluid escape at the seabed, most likely gases. These fluid emissions are associated at the seafloor with high backscatter subcircular small-scale mounds, on average less than 2 m high and a few metres in diameter. Based on near-bottom video and acoustic surveys, these mounds are interpreted to be by-products of gas seepage, possibly methane-derived authigenic carbonates. The spatial...
Tipo: Text Palavras-chave: Bay of Biscay; Aquitaine Shelf; Parentis Basin; Fluid; Seepage; Acoustics.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00201/31192/29888.pdf
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Forward modeling for marine sediment characterization using chirp sonars ArchiMer
Rakotonarivo, Sandrine; Legris, Michel; Desmare, Rozenn; Sessarego, Jean-pierre; Bourillet, Jean-francois.
This paper investigates the forward modeling of chirp-sonar data for the quantitative characterization of marine subbottom sediment between 1 and 10 kHz. The forward modeling, based on a transfer function approach, included impacts of layering or impedance mismatch, attenuation, roughness, and transitional layers, i.e., continuous impedance variations. The presented approach provided the best compromise between the number of available geoacoustic parameters from chirp-sonar data and the subbottom modeling accuracy. The forward model was tested on deep-sea chirp-sonar data acquired at a central frequency of 3.5 kHz. Comparisons between synthetic and experimental seismograms showed good agreement for the first 15 m of buried layers. Performance of the...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00039/15053/12380.pdf
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Geomorphological classification in Bay of Biscay. Morpho-sedimentary mapping of the seabed in selected areas ArchiMer
De Chambure, Laurent; Bourillet, Jean-francois; Bartel, Claire.
Les coraux d’eau froide, contrairement aux coraux tropicaux, n’ont pas besoin de lumière et peuvent se développer en profondeur. Les espèces constructrices comme Lophelia pertusa et Madrepora occulata ont une distribution mondiale et sont présentes de la Norvège à la Grèce sous forme de monts carbonatés ou de récifs. Menacés par l’évolution des conditions environnementales et les actions anthropiques, les coraux d’eau froide sont actuellement classés comme écosystème vulnérable par plusieurs institutions internationales. Dans les eaux européennes, les indicateurs pour mesurer l’impact des pêcheries et l’efficacité des mesures de protection manquent encore. Le projet européen CoralFish vise à étudier l’interaction entre les coraux, les poissons et les...
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Ano: 2013 URL: http://archimer.ifremer.fr/doc/00249/36033/34570.pdf
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Instabilities and deformation in the sedimentary cover on the upper slope of the southern Aquitaine continental margin, north of the Capbreton canyon (Bay of Biscay) ArchiMer
Gonthier, E; Cirac, P; Faugeres, J; Gaudin, Mathieu; Cremer, M; Bourillet, Jean-francois.
Acoustic and core data have recently been collected on the shelf break and the upper part of the slope of the south Aquitaine continental margin. They reveal the major role played by mass-flow gravity processes in deposit erosion and redistribution, modelling of the sea-bed, and transfer of sediment toward the deep-sea. The study region is bounded in the south by the Capbreton canyon. The northern area, which shows a smooth morphology, is characterised by small-scale deformations due to sediment creep or low-amplitude slide processes. The deformations are associated with mini listric-like faults that bound packets of sediments in which the deposit geometry is typical of constructional sediment waves. These sediment waves result from the interaction of...
Tipo: Text Palavras-chave: Sediment transfer; Mass flows; Sediment wave; Continental slope; Canyon; Bay of Biscay.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3960.pdf
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Integrating Prior Knowledge and Locally Varying Parameters with Moving-GeoStatistics: Methodology and Application to Bathymetric Mapping ArchiMer
Magneron, Cedric; Jeannee, Nicolas; Le Moine, Olivier; Bourillet, Jean-francois.
The paper aims at presenting an innovative methodology, called M-GS (M-GeoStatistics), which is fully dedicated to the local optimization of parameters involved in variogram-based models. M-GS considers the structural and computational parameters as a set of dependant parameters to be spatially optimized. The optimization process, which may be guided by objective or subjective criteria, is carried out during a M-structural analysis phase that leads to a set of spatially variable structural and computational parameters. The methodology is applied for bathymetry mapping. The availability of accurate seafloor estimates is essential for numerous oceanographic projects, including hydrographic, oceanographic and biological models, sedimentary processes, etc....
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00071/18200/15768.pdf
Registros recuperados: 44
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